Which is to say that Petroglyph’s sci-fi real-time strategy game Grey Goo [official site] is holding a free trial weekend on Steam, letting all and sundry play the whole dang game until Sunday afternoon. Alec enjoyed a beta version back before the game came out in January, and maybe you’ll dig it too. If you do, it’s on sale for keepsies.

Right-o! Grey Goo’s a base-building RTS with three factions scrapping on a distant planet, gathering resources and teching up across missions and multiplayer matches. You know: an RTS. It’s been out for long enough now that surely a commenter or two will have given it a fair bit of time and could share findings with the rest of us?

You should now see Grey Goo in your Steam Library, waiting to be installed. Or clicking this link should make Steam pop into life and say “Oh, yes! I can do that! I’ll install that for you!” You’ll have until 9pm on Sunday (1pm Pacific time) to play as much as you can/please of the full game. The 60% discount which brings Grey Goo down to £11.99 runs until Monday.

First-person melee murderfest Chivalry: Medieval Warfare is also free to try this weekend on Steam and has a sale too, I should also mention, but that’s a far more common event so it just gets a mention at the bottom of another post.